Norton Gemini Surface Grinding Segment, Type 31, Series: 53A, 11-1/4 in Width, 6 in Height, 2-1/4 in Thickness, 30 Grit, Aluminum Oxide Abrasive, G Hardness Grade, Vitrified Bond, ME30777 Blueprint Number, Applicable Materials: Brass, Bronze, Cast Iron, Ductile Iron, Gray Iron, Soft Carbon Steels and Tool Steel, For Chuck Type: Hanchett, Mattison, Norton, Cortland and Cortland Bonus, Porous Porosity